My Pi was running happily for a few months, then it died (kernel panic, hang) and wouldn't reboot. It seemed the card was corrupted.
I put in a new SD card installed raspbian from scratch and got it up and running again, but after less than 24 hours it's pretty much died again, and everything seems corrupted (e.g. can't run many commands, syslog has binary junk in etc.).
The first kernel messages that indicate a problem are:
Feb 26 11:37:28 raspberrypi kernel: [60767.540746] mmc0: Timeout waiting for hardware interrupt.
Feb 26 11:37:28 raspberrypi kernel: [60767.540938] mmcblk0: error -110 transferring data, sector 3466352, nr 8, cmd response 0x900, card status 0x200b00
Feb 26 11:37:28 raspberrypi kernel: [60767.540961] mmcblk0: retrying using single block read
Feb 26 11:37:31 raspberrypi kernel: [60770.762385] mmcblk0: error -110 transferring data, sector 3466352, nr 8, cmd response 0x900, card status 0x0
Feb 26 11:37:31 raspberrypi kernel: [60770.762429] blk_update_request: I/O error, dev mmcblk0, sector 3466352
Feb 26 11:37:34 raspberrypi kernel: [60773.983861] mmcblk0: error -110 transferring data, sector 3466353, nr 7, cmd response 0x900, card status 0x0
Is it likely that the controller is broken and I need a new Pi?
The device has a couple of w1 thermometers and a pimote controller attached, but those devices were functioning fine until the crash.
(I'm aware there is a similar question but that focuses more on whether pulling the power cable out would have damaged the card - I have not had a power cut, nor pulled the power cable out.)
Edit
I've been asked about the specifics of the sd card in use. The first one was unbranded and I have no idea where I got it. When I plugged it in my computer it caused hangs trying to mount partitions and some partitions had lost their type. I didn't think much about it at the time assuming it to be at fault, so I binned it and set up again on the 2nd card.
The second one is Kingston sdhc 16gb. other markings inlcude 1246PW1358P
and it has a 4 in a circle. Putting it into my ubuntu machine shows the boot partition is intact but the main partition is of type "unknown" now and is unmountable. It also seems to have broken the card because deleting all partitions and trying to format gives an error:
mkfs.fat 3.0.26 (2014-03-07)
stderr: `mkfs.vfat: failed whilst writing FAT
(udisks-error-quark, 0)